2-P Tsunami Laserstability

[Philipp Bethge]

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Dear all,

I am building a two-photon system around a Millenia 15W pumping a Tsunami
from Spectra-Physics. I do have some issues concerning the beam pointing
stability, especially on a day to day basis since I have to use those M1 and
M10 mirrors to optimise output power. So for this I am planning to include a
beam stabiliser consiting of quadrant detectors and piezo mirror mounts.
In additon, the beam profile is eliptical so that, after telescope
expansion, its tough to align it through pinholes. A fiber would be great,
but that only exists for 800+-10nm. I tried cylindrical lenses and a spatial
filter but I am not happy with neither solutions.

I was wondering what your experience with the Tsunami is and if there are
any suggestions to make my life easier.


thanks alot and happy new year

Philipp

[Craig Brideau]

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We have a 10-year-old Tsunami that continues to be a solid workhorse for
us.  The key is to have a fairly thermally stable room and a good solid
optical table under it.  You will have slight power variation from day to
day; the easiest way to deal with this is to use an external power
controller.  I use a simple half-waveplate and polarizing beamsplitter cube
arrangement.  We use a power meter to measure the power at the input to the
microscope before each experiment, then use the power controller to set the
input power level.  This way even if the Tsunami is a bit up or down on a
given day the controller can compensate for it.  This assumes you don't
need every last mW out of the Tsunami for your experiment so the controller
has some 'breathing room'.
As for the cavity mirrors, I rarely touch the front cavity mirror (output
coupler) since that alters the beam pointing substantially.  I usually only
need to tweak them slightly on a seasonal basis.  The back cavity mirrors
get adjusted almost every day a small amount to optimize power for a
specific tuning wavelength.  If you don't tune your Tsunami around much you
won't need to do this very often if your room is temperature stable.
Also, get good temperature-resistant mounts for your steering mirrors.
 I've had good results with the relatively inexpensive Thorlabs Polaris
mounts, and I'm sure Newport and others make similar mounts.
We actually use pinholes to maintain our beam alignment and since switching
to the temperature stable mirror mounts it has been much more consistent.
Key take-home message; you need a temperature stable room to get good
pointing stability.

Craig

On Fri, Jan 6, 2012 at 7:38 AM, SUBSCRIBE CONFOCALMICROSCOPY Philipp Bethge
<[hidden email]> wrote:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> Dear all,
>
> I am building a two-photon system around a Millenia 15W pumping a Tsunami
> from Spectra-Physics. I do have some issues concerning the beam pointing
> stability, especially on a day to day basis since I have to use those M1
> and
> M10 mirrors to optimise output power. So for this I am planning to include
> a
> beam stabiliser consiting of quadrant detectors and piezo mirror mounts.
> In additon, the beam profile is eliptical so that, after telescope
> expansion, its tough to align it through pinholes. A fiber would be great,
> but that only exists for 800+-10nm. I tried cylindrical lenses and a
> spatial
> filter but I am not happy with neither solutions.
>
> I was wondering what your experience with the Tsunami is and if there are
> any suggestions to make my life easier.
>
>
> thanks alot and happy new year
>
> Philipp
>

[Philipp Bethge]

*****
To join, leave or search the confocal microscopy listserv, go to:
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
*****

Dear Craig,

thanks alot for your extensive answer!
In fact, I am using mirrorholders from Newport that are supposed to be
rather temperature insensitive.
I am controlling the intensity of the 2P light by using a Pockels Cell
and I have an excess of power so that is not a problem.
I was just wondering if there are suggestions on how to shape the
tsuami's output beam profile in a way that it is easier to handle. I
know that the MaiTais have a beam pointing stabilizer and a cylindrical
lens telescope to provide a round, TEM00 beam, low divergence and beam
pointing stability. so this is a great beam to work with and I was
wondering if people have had similar problems before and found solutions
that I havent thought about.
I will start by monitoring the room's temperature fluctuations, thanks
for the advice!

Everybody have a great week,

Philipp

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> We have a 10-year-old Tsunami that continues to be a solid workhorse for
> us.  The key is to have a fairly thermally stable room and a good solid
> optical table under it.  You will have slight power variation from day to
> day; the easiest way to deal with this is to use an external power
> controller.  I use a simple half-waveplate and polarizing beamsplitter cube
> arrangement.  We use a power meter to measure the power at the input to the
> microscope before each experiment, then use the power controller to set the
> input power level.  This way even if the Tsunami is a bit up or down on a
> given day the controller can compensate for it.  This assumes you don't
> need every last mW out of the Tsunami for your experiment so the controller
> has some 'breathing room'.
> As for the cavity mirrors, I rarely touch the front cavity mirror (output
> coupler) since that alters the beam pointing substantially.  I usually only
> need to tweak them slightly on a seasonal basis.  The back cavity mirrors
> get adjusted almost every day a small amount to optimize power for a
> specific tuning wavelength.  If you don't tune your Tsunami around much you
> won't need to do this very often if your room is temperature stable.
> Also, get good temperature-resistant mounts for your steering mirrors.
>   I've had good results with the relatively inexpensive Thorlabs Polaris
> mounts, and I'm sure Newport and others make similar mounts.
> We actually use pinholes to maintain our beam alignment and since switching
> to the temperature stable mirror mounts it has been much more consistent.
> Key take-home message; you need a temperature stable room to get good
> pointing stability.
>
> Craig
>
> On Fri, Jan 6, 2012 at 7:38 AM, SUBSCRIBE CONFOCALMICROSCOPY Philipp Bethge
> <[hidden email]>  wrote:
>
>> *****
>> To join, leave or search the confocal microscopy listserv, go to:
>> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>> *****
>>
>> Dear all,
>>
>> I am building a two-photon system around a Millenia 15W pumping a Tsunami
>> from Spectra-Physics. I do have some issues concerning the beam pointing
>> stability, especially on a day to day basis since I have to use those M1
>> and
>> M10 mirrors to optimise output power. So for this I am planning to include
>> a
>> beam stabiliser consiting of quadrant detectors and piezo mirror mounts.
>> In additon, the beam profile is eliptical so that, after telescope
>> expansion, its tough to align it through pinholes. A fiber would be great,
>> but that only exists for 800+-10nm. I tried cylindrical lenses and a
>> spatial
>> filter but I am not happy with neither solutions.
>>
>> I was wondering what your experience with the Tsunami is and if there are
>> any suggestions to make my life easier.
>>
>>
>> thanks alot and happy new year
>>
>> Philipp
>>

[Craig Brideau]

*****
To join, leave or search the confocal microscopy listserv, go to:
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
*****

My Tsunami has a pretty round beam, it's about 1.1 so I don't bother
conditioning it.  If you measure the width/height ratio you can just pick
up a pair of cylindrical achromats (USE ACHROMATS!) with focal-length
ratios along the lines of your ellipticity.  That should nicely circularize
it for you.  Put one lens on an adjustable rail or translation stage so you
can fine focus.  Also, the smaller the absolute focal lengths are the more
'twitchy' your focus adjustment will be.  An example:
Say your beam is 1.5 to 1.  This means you either need to minimize the long
axis or enlarge the short axis.  Take the time to think whether you need
your spot to be bigger or smaller downstream before you pick what to do!
 Get cylindrical achromats of 150 and 100mm focal length.  Stick them in
the beam roughly 250mm apart.  Using a mirror, shoot the beam (carefully) a
great distance and adjust the distance between the lenses until you have a
consistently round beam.  Use an IR detector card or white paper and move
it along the beam, ensuring it is consistently round and correctly sized
all the way from the front of the telescope to at least a few meters away.
If you want a bigger beam put the 100 first then the 150, aligned with the
short axis (magnifier).  Otherwise put the 150 first then the 100 aligned
with the long axis (reducer).

Hope this helps!

Craig


On Sun, Jan 8, 2012 at 8:26 AM, Philipp Bethge <[hidden email]>wrote:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/**wa?A0=confocalmicroscopy<http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy>
> *****
>
> Dear Craig,
>
> thanks alot for your extensive answer!
> In fact, I am using mirrorholders from Newport that are supposed to be
> rather temperature insensitive.
> I am controlling the intensity of the 2P light by using a Pockels Cell and
> I have an excess of power so that is not a problem.
> I was just wondering if there are suggestions on how to shape the tsuami's
> output beam profile in a way that it is easier to handle. I know that the
> MaiTais have a beam pointing stabilizer and a cylindrical lens telescope to
> provide a round, TEM00 beam, low divergence and beam pointing stability. so
> this is a great beam to work with and I was wondering if people have had
> similar problems before and found solutions that I havent thought about.
> I will start by monitoring the room's temperature fluctuations, thanks for
> the advice!
>
> Everybody have a great week,
>
> Philipp
>
>
>  *****
>> To join, leave or search the confocal microscopy listserv, go to:
>> http://lists.umn.edu/cgi-bin/**wa?A0=confocalmicroscopy<http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy>
>> *****
>>
>> We have a 10-year-old Tsunami that continues to be a solid workhorse for
>> us.  The key is to have a fairly thermally stable room and a good solid
>> optical table under it.  You will have slight power variation from day to
>> day; the easiest way to deal with this is to use an external power
>> controller.  I use a simple half-waveplate and polarizing beamsplitter
>> cube
>> arrangement.  We use a power meter to measure the power at the input to
>> the
>> microscope before each experiment, then use the power controller to set
>> the
>> input power level.  This way even if the Tsunami is a bit up or down on a
>> given day the controller can compensate for it.  This assumes you don't
>> need every last mW out of the Tsunami for your experiment so the
>> controller
>> has some 'breathing room'.
>> As for the cavity mirrors, I rarely touch the front cavity mirror (output
>> coupler) since that alters the beam pointing substantially.  I usually
>> only
>> need to tweak them slightly on a seasonal basis.  The back cavity mirrors
>> get adjusted almost every day a small amount to optimize power for a
>> specific tuning wavelength.  If you don't tune your Tsunami around much
>> you
>> won't need to do this very often if your room is temperature stable.
>> Also, get good temperature-resistant mounts for your steering mirrors.
>>  I've had good results with the relatively inexpensive Thorlabs Polaris
>> mounts, and I'm sure Newport and others make similar mounts.
>> We actually use pinholes to maintain our beam alignment and since
>> switching
>> to the temperature stable mirror mounts it has been much more consistent.
>> Key take-home message; you need a temperature stable room to get good
>> pointing stability.
>>
>> Craig
>>
>> On Fri, Jan 6, 2012 at 7:38 AM, SUBSCRIBE CONFOCALMICROSCOPY Philipp
>> Bethge
>> <[hidden email]>  wrote:
>>
>>  *****
>>> To join, leave or search the confocal microscopy listserv, go to:
>>> http://lists.umn.edu/cgi-bin/**wa?A0=confocalmicroscopy<http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy>
>>> *****
>>>
>>> Dear all,
>>>
>>> I am building a two-photon system around a Millenia 15W pumping a Tsunami
>>> from Spectra-Physics. I do have some issues concerning the beam pointing
>>> stability, especially on a day to day basis since I have to use those M1
>>> and
>>> M10 mirrors to optimise output power. So for this I am planning to
>>> include
>>> a
>>> beam stabiliser consiting of quadrant detectors and piezo mirror mounts.
>>> In additon, the beam profile is eliptical so that, after telescope
>>> expansion, its tough to align it through pinholes. A fiber would be
>>> great,
>>> but that only exists for 800+-10nm. I tried cylindrical lenses and a
>>> spatial
>>> filter but I am not happy with neither solutions.
>>>
>>> I was wondering what your experience with the Tsunami is and if there are
>>> any suggestions to make my life easier.
>>>
>>>
>>> thanks alot and happy new year
>>>
>>> Philipp
>>>
>>>